1. Field of the Invention
The present invention relates to an electromagnetic relay having a coil mounted to an angular yoke having a first leg perpendicular to the coil axis and a second leg parallel to the coil axis with an armature and an armature retaining spring provided at the yoke second leg.
2. Description of the Prior Art
Electromagnetic relays are known having coil members serving as a base body and carrying windings between a pair of flanges with a pocket-shaped contact chamber being provided at the first flange. An angular yoke has a first leg perpendicular to the coil axis and is coupled to a core extending from the interior of the coil, the first leg forming a terminal spine at its free end. A second leg of the angular yoke extends parallel to the coil axis above the winding and has a plate-shaped armature seated at a bearing edge at the free end of the second yoke leg. The armature forms a working air gap at an end face of the coil core and at the first coil flange. An armature retaining spring has a first portion secured to the yoke and a second portion secured to the armature. A third portion of the armature retaining spring includes contacts and extends into the contact chamber. A protective cap covers the coil member and other relay parts.
The above-described relay is disclosed, for example, by German Utility Model No. 82 35 283. The disclosed relay includes an armature retaining spring disposed arcuately over an armature bearing, and having a first portion of the retaining spring lying flat against an upper surface of the second yoke leg. The armature retaining spring is, thus, fastened behind the bearing edge on the broad yoke leg, making subsequent adjustment of the spring and setting of the armature restoring force impossible. It is therefore not possible to set the relay for optimum operation. Moreover, since the disclosed relay has a current carrying yoke which serves as a feeder for the armature retaining spring, the dielectric strength between the yoke and the winding is inadequate for some applications.
As proposed in an earlier German Patent Application, No. P 35 06 354, in such cases an insulating cap is plugged into the wound coil member prior to the attachment of the yoke. This requires, however, that an additional part be manufactured and assembled in the insulating cap. Furthermore, it is difficult to seal such relay. In particular, it is not possible to achieve a tight closure of the coil winding from the contact chamber by the use of a casting compound, since the armature retaining spring lies against the second yoke leg and does not provide separation of the winding space from the movable relay parts.